Tracer type flowmeter and method using two or more injected trace materials

Abstract

An improved flowmeter apparatus and method for accurately determining the liquid flow rate in a conduit and the mass flow rate of selected pollutant components entrained in the flow stream characterized by injecting at least two trace materials into the flow stream at a plurality of locations and, after allowing adequate time for the trace materials to reach a downstream sampling location, collecting a plurality of samples of liquid from the flow stream containing the trace materials. By comparing the concentrations of the trace materials found in the sample, the degree of mixing of the trace materials in the flow stream, and hence the accuracy of the flow stream flow rate and pollutant component mass flow rate measurements, can be evaluated. Other injecting methods for more thoroughly mixing the trace materials with the flow stream are also disclosed.

What is claimed is: 
     
       1. Apparatus for measuring the rate of flow of liquid flowing in a conduit, comprising: (a) injecting means for injecting a known quantity and concentration of at least two trace materials into the liquid;   (b) sample collecting means arranged in the liquid downstream from said injecting means for collecting at least one sample containing the liquid and a concentration of said trace materials;   (c) concentration determining means for determining said concentration of said trace materials in said sample;   (d) comparing means for comparing said concentration of said trace materials in said sample; and   (e) calculating means for calculating the flow rate of the liquid as a function of said trace material concentrations in said sample.   
     
     
       2. Apparatus as defined in claim 1, wherein said injecting means introduces said two trace materials at different locations in the conduit, respectively. 
     
     
       3. Apparatus as defined in claim 1, wherein said injecting means introduces at least one of said trace materials at different locations in the conduit. 
     
     
       4. Apparatus as defined in claim 1, wherein said sample collecting means obtains a plurality of samples simultaneously. 
     
     
       5. Apparatus as defined in claim 1, wherein the liquid contains a concentration of at least one pollutant component, and further comprising pollutant analyzing means for determining said pollutant component concentration in said sample. 
     
     
       6. Apparatus as defined in claim 5, and further comprising means for determining the mass flow rate of said at least one pollutant component based on said liquid flow rate and said pollutant component concentration. 
     
     
       7. Apparatus as defined in claim 1, wherein said trace materials include at least two florescent dyes. 
     
     
       8. Apparatus as defined in claim 1, and further comprising mixing means intermediate said injecting means and said sample collecting means for mixing said liquid and said trace materials. 
     
     
       9. Apparatus as defined in claim 8, wherein said mixing means include mixing baffles mounted on the conduit. 
     
     
       10. Apparatus as defined in claim 1, wherein said injecting means comprises two pumps. 
     
     
       11. Apparatus as defined in claim 1, wherein said injecting means comprises two drip bags. 
     
     
       12. Apparatus as defined in claim 1, wherein said trace material is injected with pressurized air. 
     
     
       13. Apparatus as defined in claim 1, and further including control means for automatically triggering the operation of said injecting means and said sample collecting means. 
     
     
       14. A method for measuring, with a known degree of uncertainty, the rate of flow of a liquid flowing in a conduit, comprising: (a) injecting a known quantity and concentration of at least two trace materials into the liquid;   (b) collecting at least one sample of said liquid containing a concentration of said trace materials;   (c) determining said concentration of said trace materials in said sample;   (d) comparing said concentration of said trace materials in said sample, whereby the degree of mixing of said trace materials in the liquid is determined; and   (e) calculating the flow rate of the liquid as a function of said trace material concentrations in said sample.   
     
     
       15. The method as defined in claim 14, and further including: (e) determining the concentration of a pollutant component contained in said liquid; and   (f) determining the mass flow rate of said pollutant component as a function of said pollutant component concentration and said liquid flow rate.   
     
     
       16. The method as defined in claim 14, wherein said calculated flow rate is based on an average of said trace material concentrations in said sample.